The general effect of externally-applied electrical energy on the operation of the central nervous system, particularly for control of pain, has been observed since the early 1900's. The use of electrical energy as a predictable, reliable treatment for control and/or elimination of pain, however, has not heretofore been very successful. In general, the technology in this art area has remained relatively static for a considerable period of time.
The lack of success with electrical pain control devices is due to a large extent to the imperfect understanding of how the phenomenon of pain is produced, transmitted and finally recognized by the brain. There are several current theories on pain, the most recent and perhaps most widely accepted of which is the gate control theory, as described in the article by Melzack and Wall entitled "Pain Mechanisms, A New Theory;" appearing in Science vol. 150 at p. 971 (1965). This theory, in its simplest form, proposes the existence of a particular type of cell, referred to as "substantia gelatanosa", or simply, T-cells, which are located between the large and/or small nerve fibers and the biologic system which transmits any nerve stimulus to the brain.
Under the gate control theory, the pain stimulus is transmitted to the T-cells and eventually to the brain in the form of electrical pulses. Extraneous electrical pulses, such as those produced by a pain control device, when directed through the T-cells into the large nerve fibers, exert an inhibiting or blocking effect on the transmission of pain impulses to the brain from both the small and large nerve fibers, hence reducing or eliminating the recognition and subsequent experience of pain.
According to this theory, the extraneous electrical pulses must be accurately delivered to specific nerve endings, and it has been found experimentally that careful, precise location of the electrodes of a pain control device has improved their performance.
Nevertheless, the gate control theory does not account for all of the phenomena in the experience of pain, and the precise physical manner in which pain impulses are recognized and transmitted by the human body is still imperfectly understood. Further, the amount of relief provided by prior art electrical pain control devices varies significantly, largely for unknown reasons. It is not currently understood why some patients respond favorably to pain control devices and others do not. Hence, progress in the design of electrical pain control devices is still often obtained through intuition, experimentation, and generally empirical methodology.
Furthermore, at the time of the present invention, there were relatively few guidelines concerning the correct pulse configuration, pulse deviation and pulse rate, primarily because of the lack of theoretical understanding of the pain phenomenon.
Additionally, prior art devices have been found to be susceptible to the presence of large spikes in the pulses applied to the user's body, caused either by very low skin resistance or the inherent operation of the electrical circuit generating the pulses. The possibility of such current spikes, particularly at the rise and fall of the pulses, has prevented wide use and/or acceptance of such devices because of the health hazard involved.
The present inventors, however, after reviewing the experimental results obtained by many prior art devices and after a substantial amount of their own experimentation, have established operating parameters for the pulsed output of a pain control device which has provided substantially improved results. The inventors have designed and built a circuit which is capable of meeting the established parameters, and which eliminates, in a relatively inexpensive manner, the possibility of spikes in the output of the device. This circuit, which is described in detail hereinafter, was developed in accordance with the following objects.
It is a general object of the present invention to provide an electrical pain control and/or muscle stimulating device which overcomes one or more of the disadvantages of the prior art noted above.
It is another object of the present invention to provide such a device which eliminates or reduces pain in affected areas of the body for a substantial percentage of users.
It is a further object of the present invention to provide such a device which is harmful to the user.
It is an additional object of the present invention to provide such a device which may be conveniently carried on the person of the user.
It is a still further object of the present invention to provide such a circuit which operates for extended periods of time without the necessity of battery recharge or replacement.
It is yet another object of the present invention to provide such a device which can be used for different types of pain.
It is an additional object of the present invention to provide such a circuit which eliminates the possibility of spikes in the pulse output of the apparatus.
It is a further object of the present invention to provide such a device which produces maximum reduction of pain with minimum discomfort to the user.
It is a still further object of the present invention to provide such a device which takes advantage of the actual operation of the pain stimulus and transmission system of the human body.
It is an additional object of the present invention to provide such a device which can be conveniently used to retrain damaged muscles.
It is an additional object of the present invention to provide such a device which can be controlled remotely.